Treatment of hydrocarbons



H. L. HAYS TREATMENT OFIHYDROCARBONS Filed Sept. 2, 1941 June 1945.

AVIATION GASOLINE HARRISON LOWE HAYS B TTORNEYI HCI GAS 1o STORAGE 6 FURNACE CATALY TIC ISOMERIZATION Patent ed :Iune 12,1945

, 2,378,079 TREATMENT OF nmaocannons Harrison L. Hays, Bartlesville, kla., assig'nor to Phillips Petroleum Company, a corporation of Delaware Application September 2, 1941,'Serial No. 409,282

2 Claims. (Cl. 196-28) terial and in the presence of hydrogen chloride, to reactionpressure' and temperature conditions of the order of 0 to 500 pounds or more per square This invention relates to themanufacture of higher octane number hydrocarbons from lower octane number. hydrocarbons and more particularly to the manufacture of aviation and/or motor fuels of high octane number from a charge stock which may-contain any combination of the hydrocarbons in the natural gasoline range in any concentration whatsoever.

The principal object of this invention is to produce high octane number normally liquid hydrocarbons from relatively low octane number normally liquid hydrocarbons, preferably those usually to be found in natural gasoline stock.

Another object is to produce high octane number hydrocarbons suitable for use as aviation and motor fuels, from a charge stock which comprises any combination. of the hydrocarbons in the natural gasoline range in any concentration whatsoever.

Numerous other objects of the invention will more fully hereinafter appear.

According to this invention, a natural gasoline feed stock is first subjected to desulfurization, in

the presence of a suitable desulfurization catalyst such as bauxite impregnated with sodium-hydroxide, under reaction pressure and temperature conditions of the order of from 0 toabout loo pounds per square inch and 500 to 800 F.,

such that decomposition reactions are slight and reactions.

inch and 0 to 1000 F., respectively. These conditions are maintained such that decomposition reactions are slight, and preferably less than 5 per cent of the charge stock undergoes splitting The isomerization reaction is favored considerably if the temperatures which are used .in conjunction with reasonably high pressures are maintained well below those at which decom-, position usually begins. Therefore, pressures and temperatures of the order of 50 to 300 pounds per square inch and 200 to' 700 F.', respectively, seem to be preferable inpromoting the isomerization reaction.

As the isomerization catalyst, there may be used any'meta'llic halide capable, underthe reaction conditions employed, of effecting isomerization of normalhydrocarbons of the molecular chloride is used.

that less than 5 per .cent and preferably less than 2 per cent of the charge undergoes splitting -ployed, wherein desulfurized hydrocarbons'in the aviation or motor fuel range are separated from those which are of both lower and higher volatility. The-motor fuel or aviation fuel cut is now subjected to catalytic isomerization. However, a

portion of this stream may be recycled to the de-' sulfurizatlon step for process control.

In the catalytic isomerization step, the motor fuel or aviation fuel fraction is subjected, in the presence of a suitable catalyst, such as someone ofthe metallic halides,'aluminum chloride, 'for example, carried on a satisfactory supporting madensible hydrocarbons (mainly-isobutane) lighter isomerization of branch chainhydrocarbons to more branched forms. Generally an amphoteric metal halide is employed. It. is preferred to use an aluminum halide such as aluminum chloride,

aluminum bromide, tc. Generally aluminum The isomerizationis carried out in the presence of appreciable amounts of the hydrogen halide corresponding to the isomerization catalyst.

Thus hydrogen chloride is used when aluminum chloride is employed, hydrogen bromide when aluminum bromide is used, etc.

Following isomerization, the isomerization reaction mixture is treated to separate it into various fractions, including a fraction of con-- than those of aviation or motor fuel grade, a fraction of non-condensible normally gaseous hydrocarbons (propane and lighter) containing gaseous hydrogen chloride, a fraction comprising hi hly branched chain hydrocarbons of aviation fuel molecular weights, which is suitable for, use as, or in the preparation of, aviation gasoline, and at least one fraction of branched chain hydrocarbons of higher molecular weight than the aviation range. The portion of higher molecular weight than aviation grade may, if desired,

be resolved into ,a fraction of hydrocarbons of motor fuel molecular weight and a still heavier fraction which may be withdrawn from the system as a by-productand put to any desired use.

7 It has been found to be particularly advantageous to recycle at least asportion of and preferably all of the above-mentioned fraction .of

ably neutralized, prior to or after formation, by

. means of an aqueous solution of an alkali capable of neutralizing the hydrogen chloride therein,

such as aqueous sodium hydroxide. In this way the traces of hydrogen chloride appearing in this fraction are removed and are prevented from appearing in the final aviation fraction and in any motor fuel fraction which may be prepared.

The process of this invention may be carried forward in equipment such as is shown in the drawing, which is a diagrammatic view of the various processing elements, not drawn to scale, and illustrate one means by which the process may be practiced.

With reference to the drawing, a natural gasoline feed stock, as heretofor described, is introduced through conduit I together with insufliciently desulfurized recycle stock from conduit 44. The total feed is compressed to a suitable reaction pressure by means of pump 2. This pressure is between and 100 or more pounds per square inch. Th total feed then passes through conduit 3 andthence through heat exchanger 4 and conduit 5 into preheating coil 6 which is 2:.

suitably housed in a furnace or heating mean 1. The preheated hydrocarbons then passthrough conduit 8 into a suitable catalyst case 9 where they are subjected to the desulfurizin'ginfiuence of a suitable catalyst such as bauxite impregnated with sodium hydroxide. The reaction temperature is such that the decomposition of the hydrocarbons so treated will not be more than 2 per cent by weight for contact periods corresponding to flow rates which may vary from 1 to 2 liquid volumes of feed per hour per volume of catalyst, the most suitable exact conditions being determined by trial.

.Following passage through the reaction zone, the hot reaction products passing out via conduit [0 exchange heat with the cold feed passing through exchanger 4 as heretofore mentioned.

tor fuel hydrocarbons, and heavier, is preferthat required for this purpose is removed from the system through conduit 29. The bottom product, which comprises hydrocarbons of aviation and motor fuel molecular weight and heavier, passes through conduit to separation ele- .ment, 3l where the hydrocarbons of aviation and through conduit 40 into pump 41 where they are compressed to isomerization reaction pressure and pass thence via conduit 42 into heat exchanger .l2 where they are heated to reaction temperature. Temperature control is maintained through by-passing the heat exchanger with a portion of the stream-by means of conduit 45, valve 46, and conduit 41.

stream may be recycled to the desulfurization system for the purpose of process control. The preheated isomerization feed passes from heat exchanger l2 through conduit 48 into catalyst case 49 together with light hydrocarbon vapors and hydrogen chlorid which join this stream through conduit 69. In the catalyst case the natural gasoline hydrocarbons are subjected to the influence of a suitable catalyst such as one of the metallic halides. The reaction temperature is such that decomposition of the hydrocarbons so treated will be less than'5: per cent by weight for reaction periods which may vary from about 5 to about 30 minutes, the most suitable exact conditions being determined by trial. Conditions may be maintained to vary the composition of the equilibrium mixture of reaction products in acthe hot reaction products pass via conduit 50 into .through conduit 52, pump 53, and conduit 54.

The reaction products then pass via conduit H,

exchanger l2, conduit 13, cooler I4, conduit l5,

pump l6 and conduit l1 into fractionator 18 or other suitable separation means. A portion of the reaction products may be by-passed around cooler [4 by means of valve 20 and conduit 2| for the purpose of controlling the temperature of the feed to separating means I8. In separator IB the. hydrocarbons lighter than those desiredin aviation or motor fuel fractions are separated therefrom and pass through conduit 22,

denser and cooler 23, and conduit 24 into con-.

from the accumulator 25 through conduit 25, and.

compressed by means of pump 21 to a pressure sufliciently high to permit introducing it as a reflux or cooling medium near the top of IS by means of conduit 28. A quantity in excess of exchanger 51 where they are cooled by suitable means prior to entry into separation element 55 finished product together with hydrogen chloride pass through conduit 59, condenser and cooler 50, and conduit 6! into condensate accumulator 62. A portion of the condensate is taken from accumulator 62 through conduit -63 and compressed by means of pump -84 to a pressure sufllciently high to permit its introduction as areflux or cooling medium near the top of 55 via conduit 65. The condensed portion'in excess of that required for this purpose is continuously removed from the system through conduit 66. An uncondensed portion (propane and lighter) which contains an appreciable quantity of hydrogen chloride is removed near the top of 62 and passes through conduit 61, compressor pump 68, and conduit 69 5 to its point of junction with the hot catalyst chamber ieedf Ii operations render it desirable, a portion of this unconden'sed materialflmay be vented from conduit 51 by suitable venting means, such as conduit 33 controlled by valve 99. Pump y means of valve 43 I and conduit 44 a portion of this hydrocarbon 68 may or may not be needed depending upon the desired operation pressure of catalyst case 49. Fresh hydrogen chloride make-up i provided by means of tank 10 and conduit H. The bottom product from 55 which contains the valuable constituents, together with insufliciently reacted madrocarbons are separated fromthe neutralizing solution and pass through conduit 16 into separation element 71. Conduit 18, pump 19, and conduit 80 permit recirculation of the partially used neutralizing solution. Fresh solution is introduced through conduit BI, and spent solution is removed from the system through conduit 82, valve 83, and conduit 84. The valuable hydrocarbon constituent passes through conduit 85, condenser and cooler 86; and conduit 81 into condensate accumulator 88. As in the preceding step,

a portion of this material is introduced near the top of l! by means of conduit 89. Pump 90, and

fuel which is superior from the standpoint of octane number, volatility, lead response and con-' tentof highlybranched hydrocarbons from relatively low grade natural-gasoline stock, of which an excess is available. Thus the inventionenables the conversion of low grade, relatively abun dant material for which there i little demand into aviationv gasoline. or aviation blendingstock which may be used to prepare aviation fuel of superior anti-knock qualities, to thereby meet the increasing demands for high octane aviation gasoline and to more easily meet the increasingly conduit 9| to act as a reflux or cooling medium. I

The valuable constituent in excess of that required for this purpose is removed from the system' through conduit 92, pump 93, valve 95, and conduit 96. A portion of this material, however, is recycled to the isomerization system through conduit 94 for the purpose of process control, particularly to increase the efficiency of the system. The bottom product from 9| which comprises hydrocarbons of higher molecular weight is 'removed from the system through conduit 91.

The process of the present invention presents numerous advantages. The employment of the catalytic desulfurization step prior to the"catalytic isomerization step enables the production of a higher octane product displaying superior lead response. It has been found that the presence of sulfur in appreciable amounts in the isomerization feed interferes seriously with the progress of isomerization and prevents the attainment of the stringent aviation fuel specifications.

Still another advantage is that'the process allows the production of a fraction of relatively high octane motor fuel material comprising hydrocarbons which, while above weight range for aviation. fuel, are highly branched and are eminently satisfactory for, or

in the blending of, automotive gasoline,

While the foregoing description refers to that specific embodiment of the invention which is now preferred. by me, it is to be understood that numerous changes and modifications may be made therein without departing from the inventive thought, and'that the invention i to be llmjs ited only by the spirit and theterms of the appended claims.

I claim:

1. In a process of producing high octane number highly branched chain hydrocarbons in the aviation fuel range by catalytic isomerization,

\ with a metal'halide isomerization catalyst, of a low-octane number natural gasoline charge stock containing substantial amounts of suliur,wherein said charge stock is subjected to treatment prior to isomerization to reduce the sulfur content thereof, the improvement which comprises:

subjecting such a charge stock to catalytic desulfurization' with a solid desulfurization catalyst consisting of, bauxite impregnated with sodium hydroxide, under a pressure of from about 0 to about pounds per square'inch, at a temperato produce an effluent comprising a fraction of ture of from about 500 to about 700 F.,'and under conditions such that less than 2% of the hydrocarbons charged undergo splitting reactions,

' desulfurized hydrocarbons in the aviation and flculty is overcome by catalytic desulfurization of the material undergoing catalytic isomerization.

merization feed stock is beneficial from the standpoint of the adverse poisoning effect of sulfur even in concentrations as low as 0.004% upon the isomerization catalyst. With the present invention it is readily possible to maintain the sulfur content of the isomerization feed at a value which is sufliciently low to insure an economi-- cally long catalyst life and satisfactory operation. Another advantage which accrues from the use of the desulfurization step prior to isomerization is the economy which can be secured through the use of carbon steel inequipment fabrication, particularly in that portion of the equipment employed after the desulfurization step, except in operating zones where temperatures of 1000 F. or higher compel the use of alloy steels of adequate creep stress characteristics. The presence of sulfur compounds in appreciableconcentrations causes severe corrosion of ordinary steelequipment and forces the use of expensive, difll- In addition, catalytic desulfurization ofthe isomotor f-uel range, said fraction-containing notmore than 0.01% of sulfur; fractionating said "eilluent to separate saidfraction from' lower and higher boiling material; recycling a portionof the so-separated fraction to said catalytic desulfurization step;- and subjecting the remainder of :0

the so-separated fraction directly to said catalytic isomerization.

2. In a process, of producing high octane number highly branched chain hydrocarbons in the aviation fuel range by catalytic isomerization,

with a metal halide isomerization catalyst, or a low octane number natural gasoline charge stock containing substantial amounts of sulfur, wherev v in said charge stock is subjected to treatment prior to isomerization to reduce the sulfur content thereof, the improvement which comprises: subjecting such a charee-stockto catalytic desulfurization with a solid desulfurization catalyst consisting 'of bauxite impregnated with so dium 'hydroxidepunder a pressure of from about resistant steels.

Another advantage is that the process enables the ready and economical production of aviation 0 to about 50 pounds per square inch, at a temperature of fro under con tions such that less than 2% of the hydrocar ns charged undergo splitting reactions, toproduce a hot eiiiuent comprising a fraction; of desulfurized hydrocarbons in the aviation the molecular m a bout 500 to abll lt 700 F., and

and motor fuel range, said fraction containing not more than 0;01% of suliur; cooling said hot eifiuent by heat exchange as hereinafter described; fractionating the -so-cooied efli'uent to separate said fraction of desuliurized hydrocaz vbons from lower and higher boiling material; re-

cycling a portion of the so-separated fraction to said catalytic desifliurization step; heating'the remainder of the so-separated fraction to an isomerization temperature of from about 200 to about 700 F. solely byheat exchange with said hot efliuent; and subjecting the thus-heated material directly to said catalytic isomerization.

"HARRISON L. HAYS. 

